The present invention relates to a tape cassette for use in audio, video and data recorders, and more particularly, to a tape cassette having a front cover for covering the tape stretched along an opening formed in the front surface of a casette case and a cover-locking piece for preventing the front cover from opening when the tape cassette is not in use.
Examples of the conventional tape cassette of this type include those employed in conventional VHS or .beta. system VTRs. Both of these tape cassettes have a front-cover spring for urging the front cover to pivot toward a position in which the front cover protects the tape stretched along the opening formed in the front surface thereof. In addition, the tape cassette is provided with a coverlocking piece adapted to prevent the front cover from opening when the tape cassette is not in use and to pivot in the widthwise direction of the tape cassette, and a locking spring for engaging the cover-locking piece with the front cover and urging the cover-locking piece in a direction in which the front cover is prevented from opening. When the front cover, cover-locking piece; and means for urging the respective members are applied to a compact tape cassette, problems arise in that the front cover springs require additional space and that it is necessary to extend the widthwise dimensions of the tape cassette since the cover-locking piece pivots in the widthwise direction of the tape cassette when releasing the lock. Moreover, there are many instances where the front cover springs undesirably come off during assembly of the tape cassette, which prevents the tape cassette from being easily and automatically assembled by machine. These problems are particularly prominent in the case where a plurality of springs are provided as the front-cover urging spring, the locking spring and the like, respectively.
On the other hand, it is necessary to provide an optical path aperture in a side surface portion of a tape cassette which employs a system for detecting the leading and trailing ends of a tape having a transparent tape attached to each of the leading and trailing ends thereof, as is employed in, for example, a VHS system VTR in which either one of light-emitting and light-receiving detecting means is entered into the cassette through the bottom surface thereof while the other is disposed outside of the tape cassette in opposition to the former through the tape within the tape cassette.
The optical path aperture is generally disposed at a side plate portion of the tape cassette case and can be covered, when the tape cassette is not in use, by the side plate portion of the front cover pivotally supported at the case side plate portions. However, the side plate portion will cover the optical path aperture at a predetermined distance therebetween in the case of a compact tape cassette which needs to provide the front-cover spring for urging the front cover and the cover lock for preventing the front cover from opening in the space defined between the side plate portion of the front cover and the case side plate portion which are a predetermined distance away from each other. It is contradictory, since the compact tape cassette is desirable to make the widthwise dimension thereof as small as possible.
The optical path aperture, similarly to the other openings of the tape cassette, causes dropouts since dust entering through the openings, adheres to the tape within the tape cassette. This problem is more serious, particularly, in the case of a portable tape cassette for short-wavelength and high-density recording since, in such a case, the tape cassette will be possibly carried in the pockets of clothing or the like.